Life-time roadtripper, first-time globetrotter

Canadian/American looking for international packing advice! I've only been overseas once (2005), and I remember very little:
1. Humans are sardines
2. Everything is a lot smaller in Europe
3. I *will not* want to stand out more than necessary

I was already planning to travel with just a carry-on, so discovering r/onebag is delightful. My intent is to spend 2025 traveling the world (westward) from North America. I don't need to bring work with me, and if I fill up my whole journal, I can mail it home and buy another one. I intend to buy some clothing in NZ and Germany, to dress as much like a local as is feasible, since I'll be spending several weeks or months in those two places.

Where I'm definitely spending time this year:
- New Zealand (South Island)
- Germany (Bavaria)

Where I may go along the way:
- Hawaii
- Alaska
- Guam
- South Korea (Seoul)
- UK (Leeds & Scotland)
- Ireland
- Iceland
- Greenland
- Bahamas

My first concern is that one of my shoulders is damaged, so I have to use a strapped bag or hand-carry bag, no backpack. Know of any good ones, or what styles won't scream "tourist"?

My second concern is that I don't know what I'll reasonably be able to find and/or replace in each country (like charging blocks for my phone, facemasks, toilettries, simple sewing kits). What do I *need* to bring, or at might have trouble finding in the first few days?